Commit aa9c120d for libheif

commit aa9c120d456578301d14c92124405ff9c16e9453
Author: Dirk Farin <dirk.farin@gmail.com>
Date:   Sun Dec 21 20:04:32 2025 +0100

    check that sequence track has a 'stts' box (fixes #1642)

diff --git a/libheif/sequences/track.cc b/libheif/sequences/track.cc
index 7ffa3dae..a6a44d32 100644
--- a/libheif/sequences/track.cc
+++ b/libheif/sequences/track.cc
@@ -284,6 +284,13 @@ Error Track::load(const std::shared_ptr<Box_trak>& trak_box)
   }

   m_stts = stbl->get_child_box<Box_stts>();
+  if (!m_stts) {
+    return {
+      heif_error_Invalid_input,
+      heif_suberror_Unspecified,
+      "Track has no 'stts' box."
+    };
+  }

   const std::vector<uint32_t>& chunk_offsets = m_stco->get_offsets();
   assert(chunk_offsets.size() <= (size_t) std::numeric_limits<uint32_t>::max()); // There cannot be more than uint32_t chunks.